If you use any sort of CDN on your base domain, you can’t host most other things on that same root domain. This is because these other protocols generally use A(AAA) records and those records are pointed to the CDN.
The biggest exceptions that I know of are mail and XMPP/Jabber which use MX records and SRV records respectively.
It’s annoying that new (and even old) protocols don’t work with SRV records. For example, why don’t all clients support SRV records for ftp, ssh, irc, gemini, fediverse, rsync, ntp.
In fact, I think it would be great if there was a SRV record for http/https that browsers checked. Then, we could set CDN addresses outside of the A(AAA) records as well as specify custom ports.
Do you think that the lack of SRV records is just for historical reasons, or do you think it would be annoying for every protocol to support SRV?